STM investigation of the dependence of alkane and alkane (C 18H 38, C 19H 40) derivatives self-assembly on molecular chemical structure on HOPG surface

Abstract

Alkane molecules and their derivatives are composed of alkyl chain and functional groups that dominate the interactions of intermolecule and molecule/substrate and result in different self-assemblies on solid surface. In the present paper, the self-assemblies of alkanes and alkane (C 18H 38, C 19H 40) derivatives are studied on HOPG surface at room temperature in ambient conditions by scanning tunneling microscopy (STM) to understand the structure and stability of these self-assemblies and to reveal the dependence of their self-assemblies on their chemical structures. It is found that the alkane molecules with short alkyl chains such as tridecane (C 13H 28), tetradecane (C 14H 30) and pentadecane (C 15H 32) can form lamellar structures on HOPG and be steadily imaged by STM. On the other hand, linear or herringbone structures can be observed in the self-assemblies formed by a series of derivatives of C 18H 38 and C 19H 40. The results are discussed based on STM results to understand the structures and structural stability of alkane molecular self-assemblies.